Internal combustion engines, such as those used in automobiles, typically include sections of flexible hose to convey fluids. These hoses are generally composed of rubber and/or synthetic polymers and must function in an environment susceptible to wide variations in temperature. The temperature of the engine compartment prior to engine operation may be at ambient temperature but, in use, the engine quickly achieves an operating temperature of several hundred degrees. Due to these temperature changes the tubular connections experience diametral and flexibility changes. Clamps used to secure the hose connections must accommodate these changes.
Various types of clamps have been used to secure such hoses to their associated components in such applications as internal combustion engines among others. Fixed diameter clamps do not adjust to changes in the clamped connection caused by the variations in temperature. Spring-type members have been added to fixed diameter clamps to compensate for changes due to temperature, but are inefficient and quite expensive.
Spring-type, single wire hose clamps compensate to a certain extent for diametral and material changes caused by variations in temperature. These hose clamps are typically formed into spiral loops from annealed spring wire and then are hardened and tempered. Opposed forces imposed on the ends of the wire allow the loop to be expanded against the tension of the spring wire for installation on a hose. Upon release, the loop contracts and clamps the hose. The clamp itself is configured with an unstressed loop diameter smaller than the associated hose, so that upon installation the clamp provides sufficient gripping force for a fluid-tight seal. As the hose expands during engine operation, the clamp resiliently expands and maintains a relatively constant clamping force on the hose connection. Examples of these single wire hose clamps can be found in U.S. Pat. No. 3,208,120, U.S. Pat. No. 2,180,271, U.S. Pat. No. 3,317,966, and U.S. Pat. No. 2,793,414.
These clamps must be relatively rigid so that they impose a sufficient force on the connections to achieve an effective seal. This rigidity limits the size to which the loop may be enlarged during installation without exceeding the elastic limit of the wire. The engineering compromise between the clamping forces that the spring imposes during normal use and the limit to which the clamp may be opened during installation without taking a permanent set is aggravated by the fact that the stresses imposed on the clamp during installation are concentrated at a point midway between the spring ends.
There is accordingly a need in the industry for a self-compensating hose clamp which compensates for diametral and material changes of the components due to temperature variations and which is both inexpensive and has a large diametral flexibility range for efficient installation and removal purposes.